Changing a flat tire on an automobile is generally regarded by consumers as a troublesome chore at best, and, if the flat occurs in certain locations or weather conditions, can be perceived to be a dangerous undertaking. Consequently, aerosol tire sealants and inflators packaged in aerosol containers suitable for carrying in an automobile have gained wide acceptance by consumers.
A conventional tire sealer and inflator composition is disclosed in U.S. Pat. No. 5,338,776 to Peelor et al. The composition of the patent employs two components: a sealing component consisting of an acrylic resin dissolved in a solvent and a propellant component based on a hydrochlorofluorocarbon or a hydrofluorocarbon compound. The composition of the patent is characterized in the patent as anhydrous. Ten solvents are specifically identified in the patent at column 4, lines 39 through 55 as being suitable for the tire sealer and inflator composition of the patent. With exception of methylene chloride, each of the solvents specifically identified has been classified by the State of California as an atmosphere polluting volatile organic compound ("VOC") and its release into the atmosphere is discouraged. Methylene chloride in the liquid state, although not classified as an atmosphere polluting VOC, tends to attack rubber compounds by solubilizing them. Introduction of liquid methylene chloride into the cavity of a pneumatic tire would be expected to have an adverse effect on the rubber compounds of the tire. Although the inside wall surfaces of certain tires have a polymer-membrane liner which may provide some protection against methylene chloride, additional protection would be desirable were methylene chloride to be used as a solvent in a tire sealer and inflator composition.
It would be desirable to use a nonflammable, environmentally inoffensive, essentially inert gas such as air, nitrogen (N.sub.2), carbon dioxide (CO.sub.2), or helium (He) as a propellant/inflating agent for an aerosol tire sealer and inflator. However, typical aerosol containers--designated "2Q" containers--can be pressurized to a pressure of no greater than 180 psig at 130.degree. F., a limit imposed by the United States Department of Transportation for interstate shipping of such containers. Moreover, as a practical matter, aerosol containers can be no larger than about one liter in capacity. A one liter vessel containing only an inert gas in a quantity just sufficient to meet the pressurization limit of 180 psig at 130.degree. F. would not contain sufficient gas to pressurize a conventional pneumatic automobile tire to a driveable condition.
Solvents are known which can dissolve sufficient carbon dioxide at a pressure safely contained by ordinary aerosol containers to pressurize a flat tire to a driveable condition. Certain of such carbon-dioxide solvents have vapor pressures of at least roughly 100 mm Hg at about 70.degree. F. and thus could contribute to the pressurization of a tire. Among such low-vapor-pressure carbon-dioxide solvents are furan, tetrahydrofuran, acetonitrile, acetone, methylal, methylene chloride, and 1,1-dichloro-1-fluoroethane. Of the compounds listed, furan, tetrahydrofuran, acetonitrile, acetone, and methylal are flammable and potentially explosive in an air pressurized tire. The solubility of carbon dioxide in 1,1-dichloro-1-fluoroethane is considerably less than the other compounds listed. Moreover, 1,1-dichloro-1-fluoroethane has been classified as an atmosphere polluting volatile organic compound by the State of California and is relatively expensive to manufacture, which prohibits the use of substantial quantities of the compound in an aerosol container. As noted above, methylene chloride has a high solubility parameter with respect to rubber compounds and has the potential in the liquid state to soften or degrade the rubber compounds of rubber tires.
A need exists for an effective and inexpensive tire sealant and inflating composition which is essentially nonflammable, essentially nonexplosive, and essentially non-stratospheric-ozone depleting and which does not contribute unduly to global warming and does not contain high levels of atmosphere polluting volatile organic compounds.